Many of old vehicle brake devices are hydraulic ones. However, with an introduction of sophisticated brake control arrangements such as anti-lock brake systems (ABS), electric brake devices, which are capable of carrying out such sophisticated brake control without the need for a complicated hydraulic circuit, are becoming popular today. An electric brake devices includes an electric linear motion actuator including a linear motion mechanism for converting the rotary motion of an electric motor to a linear motion of brake pads, and is configured such that when the electric motor is activated by e.g. a signal generated when a brake pedal is depressed, the brake pads are linearly driven by the linear motion actuator and pressed against a brake disk, thus applying a braking force to the wheel (see e.g., the below-identified Patent document 1).
In this electric brake device, cyclic fluctuations in braking force could occur during braking if the brake disk becomes worn unevenly, which could result in abnormal vibration of the vehicle body.
The below-identified Patent document 2 proposes to reduce fluctuations in braking force and thus to prevent abnormal vibration of the vehicle body, by detecting the frequency of the cyclic fluctuations in braking force generated by the electric brake device, and actuating the electric brake device in opposite phase to the braking force fluctuations if the frequency detected is proportional to the wheel speed.